Process of preparing starch pastes



Patented Apr. 4, 1939 UNITED STATES PATENT OFFICE.

,2,15s,445 PROCESS or PREPARING STARCH PASTES John J. Willaman, Robert A. niehm. and Edward W. Clark, Bristol, Pa., ass'ignors to Bfihm & Haas Company, Philadelphia, Pa.

' No Drawing.

Application April 21, 1936,.

Serial No. 75,548

\ 17 Claims. ((31-195-114) A paste made from raw starch unmodified in' any way is unsuitable for most sizing and adhesive purposes. It is highly viscous per unit of concentration and gives a harsh, brittle finish 10 that is generally undesirable. In a paste .of workable viscosity, the concentration of starch is too low to give proper sizing or adherence. Hence, it

has .been found desirable in commercial processes of preparingsizes and adhesives to modify 15 the raw starch and increase its water solubility whereby a less viscous paste of suitable concentration is obtainable. The three common modilying processes can be classified generally as (1) by treatment with acids; (2) by treatment with m chlorine; and (3) by thejaction of the'=enzyme dlastase. The present invention is an improvement in the third method. k

In the enzyme'process as" commonly conducted, a mixture of starch-and water is heated to or 25 somewhatabove the gelatinization temperature of the starchemployed, and then cooled to the temperature best suited for the particular enzyme used. Thereafter the enzyme is added and allowed to act until the viscosity of the paste is so reduced to thedesired point- The action of the enzyme is stopped by raising the temperature to the point where the enzyme is destroyed. This process has two distinct disadvantages the necessity of cooling the paste which requires time and attention, and the difliculty in getting the enzyme thoroughly distributed throughout .'the

gelatinized starch. I

It has been proposed to obviate these disadvantages by incorporating the dlastase with the starch and water before heating to the gelatinization temperature and maintaining thetempera ture at that point during the action of the enzyme. Such a process is-possible, but very uneconomical of enzyme. Tapioca starch gelati nizes at about 63 C., wheat and potato starch'at about 65-681 (7., and corn starch at about '72'-74 C., temperatures that are from 10-30 C. above the optimum for most. diastases. Some of them" will act at these temperatures f'or a short time but are so-quickly destroyed that economically prohibitive quantities of enzyme must be used if the proper degree of modification is to be attained.

. The object of the present invention is the development of va'practiclalland economical proc- 5 es of preparing a starch paste suitable for sizing and adhesive purposes by the action on diastatic enzymes on starch. More specifically the object of. the invention is the development of a process that will permit the economical use of diastatic 10 enzymes at the gelatinization temperature of starch. These objects we have attained through our discovery of a new class of activating and protecting agents which greatly enhance the activity of diastaseat, any temperature and espe- 15 cially at the unfavorably high temperatures decribed above. We have found that very small quantities of inorganic oxidizing agents that will react with water to liberate oxygen, such as the alkali and alkaline earth metal and ammonium salts of perboric, hypochlorous and persulphuric acids, and the alkaline earth metal peroxides,

when added to a mixture of starch, dlastase and water give from threeto five times the activity of dlastase that is obtained in their absence. So- 5 dium chloride and the soluble salts of calcium are known as activating and protecting materials for dlastase. The action of the above oxidizing agents is in addition to and independent of the protective action of calcium and sodium salts and may be used either alone or in combination with these known protecting agents. By the use of our protecting agents the quantity of dlastase required in the making-of suitable size at the gelatinization temperature of starch is reduced toan amount which is economically feasible.

In, carrying out the invention any raw starch is finely powdered and added to water in the desired proportion, depending upon the use to which the paste is to be applied. The starch and water mixture should preferably be slightly acid, such as obtains with the usual commercial starch and the usual sources of water. If either the starch or the water is more than slightly alkaline, the mixture is preferably brought to a slightly acid condition. At this stage of the process the water should be maintained at a temperature below the gelatinization temperature of the starch. To the of enzyme and activating agent are added and thoroughly mixed. Any diastatic enzyme may be used. The choice will depend primarily on cost and availability, the quantity upon the degree of liquefaction desired and the type of starch em.- ployed. If The mixture of water, enzyme, starch and activator is then heated while being thoroughly stirred, to thetemperature at which the starch employed'gelatinizes, and is maintained at that temperature until the desired degree of. liquefaction is obtained. In ap lying the process commercially. it is desirable that the heating should notuextend beyond a period of thirty minutes. The quantityof enzyme employed should be such that itwili produce the desired liquefaction in that period. Shorter periods of treatment require an increase in the dosage of enzyme. v v

The exposure of any type of diastase to these temperatures for thirty minutes results in almost complete inactivation. This is especially true for pancreatic diastase and to a less degree, for fungus and malt diastases. It is nevertheless desirable in all cases, after proper liquefaction is obtained, to heat the mixture to 85 C. to insure complete inactivation of the enzyme. The bacterial enzymes are the most heat resistant of the diastases and when used a destructive temperature of 100 C. should be employed. In car-- r'ying out our process we prefer to use a malt or fungus diastase- The heat resistance of these enzymes .is such that the degree of liquefaction can be closelycontrolled by adjusting the quan tity of diastase preparation added. We prefer comes a thick, pasty mass.

fungus diastase to malt because of its lower saccharifying action. .1

In the 'processas thus described the mixture of starch, water, enzyme and activator remains as a fluid slurry until the temperature of gelatinization is reached, at which point it suddenly be- When this condition is reached stirring is stopped and heating discontinued. It is then that the enzymes begin to function and within a period of a few minutes begin to liquefy the starch to a point at whic stirring can be resumed ifdesired.

The amount of oxidizing agent that should be added cannot be given in definite quantities as it depends upon the type of starch to be'treated,

the particular diastatic enzyme used, and the choice ofr oxidizing agent. For any given reaction mixture there'is an optimum concentration for each-oxidizing a'gentg If more or less than this optimum amount is used,- less diastatic action results. This optimum concentration of oxidizing agent for'any given mixture can readily be determined by a few preliminary tests measuring theeffect that diiferent amounts of oxidizing agent have upon the enzyme activity of the preparation. Such measurements can be made by any ofthe standard methods of measuring enzyme activity. The tablesummarizes the results 'obtained'by a number of such tests on different mixtures. "Besides showing how different;

concentrations of oxidizing agent affect the activity of the'enzymes, it illustrates the magnitude of the increased activity obtainable by our new,class of stabilizers. These activities were determinedfby measuring the drop in viscosity of a. starch paste overmeasured periods of time due,

to the action of the diastase, a principle often used in measuring various enzyme activities. The

measurements'were made at temperatures varying from 60-75" C. I The figures given for relative activity are compared to an arbitrary figure except thatno oxidizing agent Emample 3.-200 grams of powdered tapioca of 100 given to the action of each enltyme in Q the absence of activator.

' I Table Activator Relative diastatic activity Enzyme 2,3

' Kind gm.

starch mg.

.. Fungus Sodium perborate.

Calcium peroxide,

. .do.. Magnesium peroxide.

asss:

Calcium hypochlorite. v

Calcium peroxide.

Sodium perborate.

Magnesium peroxide.

Fungus. Sodiumpcrborate.

nine.

The following specific examples are given to' illustrate our invention. They are given for pur-,. poses of illustration only and should not be construed as limiting the invention.

E$ample.1.-200 grams of powdered raw corn starch were stirred into 800 odor-water. 0.61

gm. of a fungus diastate preparation and 0.2-. gram of calcium. peroxide were. added and thoroughlymixed in. The temperature was then raised to 72 C. and held therefor minutes,

enzyme.

The viscosity of thersulting' paste was measured ina'viscometer pipette at a o c; and had; an outflow timeof ,12 seconds In a similar run in which no oxidizing-agent'was present, the

the stirring beingdisc'ontinued when-the starch gelatini'zed. At the end of this time, the mix ture was' heated to andheld for flve,minutes at 85 C. to insureflcomplete inactivation of the 5 resultihg'paste had an'outflow time of 100 ec-f onds.,,, ErampleiZL-A mixture of 200-gm'gof powdered rawstarch 800cc; of water, 3 gramsofactive,

malt extract and 0.4 gram of. sodiu'mperbbrate was prepared and treated as in Example 1. The

outflow time of theresulting paste was10 seconds as compared with an. outflow time of 50 seconds, for a paste-prepared under identicalconditions starch. were'stirred into 800' cc. of water. gramof afifungus diasta'sepreparation and 0.1

gram of sodium perborate were added. Thetein perature 'was then raised to C., held there; for'30'minutes and then raised to C. A control paste was prepared under the same condi tions omitting the oxidizing agent. This control paste had an outflow time of 52 seconds as compared with 31 seconds for the paste prepared in the presence of the oxidizing agent.

In a similar'run' in which 0.01 gram ammonium persulphate and 0.008 g'ramof sodiumbicarbonate (to counteract the acidity produced by the ammonium persulphatel were substituted for the sodium perborate, a paste was obtained having an outflow time of 45 seconds.

Example 4.-200 gm. raw powdered corn starch,

2.85 gm. bacterial diastase preparation, 0.05 gm.

5 sodium perborate and 800 cc. of water were thoroughly mixed, heated while stirring to 80 0.,

held at this temperature for 30'minutes, heated at 93 C. for minutes to inactivate the enzyme,

cooled to180 C. and theviscosity measured in a 10 viscometer pi'pette. The outflow time was 13 seconds. In a similar run, in whichno oxidizing agent was present, the outflow time was 43 seconds.

Example 5.--200v gm. raw powdered corn starch, 15 0.40gm. fungus enzyme preparation, 0.4 gm. calcium acetate monohydrate, 0.2 gm. calcium peroxide and 800 cc. of water were mixed, heated while stirred to 72 0., held at this temperature for 30 rninutes, heated at 85 C. for 5 minutes to inactivate the enzyme, cooled to 80 C. and is viscosity measured. The outflow time was 24 seconds. In a similar run, in which no calcium peroxide was added the outflow time was 42 seconds. 25 In carrying out our process, it is important to select an inorganic oxidizing agent that re-. acts with water to liberate oxygen. Other typical inorganic oxidizing agents, such as potassium permanganate, potassium chlorate, solium chromate and sodium dichromate, which do not react withwater to liberate oxygen under the operating conditions described above, do not increase the action of the various disatases. It is-also important to avoidaddlng too much of the useful oxidizing agents. We have found that excessive quantities of these agents instead of stabilizv ing the enzymes, tend to destroythem and reduce .theirxactivityir In the following claims the term 'oa'ctivating amounts is intended to cover those I 1. In a process of preparlng'a starch paste by diastatic enzyme action the improvement which comprises incorporating in the reaction mixture an-activating amountof an -inorganic oxidizing mmonium salts of hyd h persul-phunc d.perbOric-acid,

2.v In a process of preparing a starch paste by "diastatic enzyme action the improvement which comprisesincorporatlng in the reaction mixture: an activating amountof an' alkaline earth metal peroxide.

'3. In a process of preparing a starch paste by: diastatic enzyme action the improvement which comprises incorporating in the reaction mixture an activating amount of a ,perborate.

4. In a process ,of preparing a starch paste by diastatic enzyme actionthe improvement which comprises incorporating in the reaction mixture an activating amount of sodium perborate.

5. In a process of preparing a' starch paste by diastatic enzyme action wherein the reaction is carried-out atthe gelatinizing temperature of the starch, the improvement which comprises incorporatingin'the reaction mixturean activatingarnount of an inorganic oxidizing agent that will react with water to liberate oxygen selected fromthe group consisting of the alkaline earth peroxides and alkali, alkaline earth and amagent that will react with'waterto liberate oxygen selected from the group consisting of the alkaline- ,earth peroxides and alkali, alkaline earth and monium salts of hypochlorous, persulphuric and. perboric acid.

6. In a process of preparing a starch paste by diastatic enzyme action wherein the reaction is carried out at the gelatinizing temperature of the 5 starch, the improvement which comprises incorporating in the reaction mixture an activating amount of an alkaline earth metal peroxide.

7. In a process of preparing a starch paste by diastatic enzyme action wherein the reaction is 10 carried out at the gelatlnizing temperature of the starch, the improvement which comprises incorporating in the reaction mixture an activating amount of a perborate.

8. In a process of preparing astarch paste by 15 diastatic enzyme action wherein the reaction is carried out at the gelatinizing temperature of the starch, the improvement which comprises incorporating in the reaction mixture an activating amount of sodium perborate.

9. The process of preparing a starch paste which comprises forming a mixture of starch water,

a diastatic enzyme and an activating amount of an inorganic oxidizing agent that reacts with water to liberate oxygen selected from the group 35 consisting of the alkaline earth peroxides and alkali, alkaline earth and ammonium salts of hypochlorous, persulphurid and perboricl acid, heating the mixture to the gelatinization ternperature of the starch and, after the desired '9 liquefaction is obtained, destroying the activity of the enzyme.

10. The process of preparing a starch paste suitable for sizing purposes which comprises forming a mixture of starch, water, a diastatic g5 fungus enzyme, and an activating amount of an inorganic oxidizing agent that will react with water to liberate oxygen selected from the group consisting of the alkaline earth peroxides and alkali, alkaline earth and ammonium salts of 'hypochlorous, ,persulphuric and perboric acid,

heating the mixture to the gelatinization tem- .peratureof starch, maintaining that temperature until the desired liquefaction is obtained,

and then heating to about C. until the 45 enzyme is inactivated.

11. The process of preparing a starch paste suitable for sizing purposes which comprises, forming a mixture of starch, water, a diastatic fungus enzyme, and an activating amount of an 50 alkaline earth metal peroxide, heating the mixture to the gelatinization temperature of starch, maintaining that temperature until the desired liquefaction is obtained, and then heating to suitable for sizing purposes which comprises forming a mixture of starch, water, a diastatic fungus enzyme, and an activating amount of sodium perborate, heating the mixture to the gelatinization temperature of starch, maintaining 70 that temperature until the desired liquefaction is obtained, and then heating to about 80 C. until the enzyme is inactivated.

14. In a process of preparing a starch size by the action'of a diastatic fungus enzyme at the 7 reaction mixture an activating amount oi an inorganic oxidizing agent that will react with water to liberate oxygen selected from the group consisting oi" the alkaline earth peroxides and alkali, alkaline earth and ammonium salts. of

hypochlorous, persulphuric and perborlc acid.

15. In a process oi'preparinz a starch size by the action of a diastatic fungus enzyme at the gelatinization temperature oi the starch, the improvement which comprises incorporating in the reactionmixture an activating amount; 01 an alkaline earth metal peroxide.

16.11; a process oi preparing a starch size by gelatinization temperature of the starch, the im-- provement which comprises incorporating in the reaction mixture an activating amount of sodium 10 perborate.

JOHN J. WIILAMAN. ROBERT A. DIEHM. EDWARD W. CLARK. 

